This application is based on French Patent Application Serial No. 0008085, filed Jun. 23, 2000, which is incorporated herein by reference.
The present invention relates to a rinsable foaming composition constituting a cream for topical application, which comprises a specific surfactant system and which exhibits good physical stability up to at least 45xc2x0 C., and to its use in the cosmetic or dermatological fields, in particular as products for cleaning or removing make-up on the skin, scalp and/or hair.
Cleansing the skin is very important in caring for the face. Cleansing must be as efficient as possible since greasy residues, such as excess sebum, the daily remnants of cosmetic products, and make-up products, in particular waterproof products, accumulate in the skin folds and can block the pores of the skin and result in the appearance of spots.
Several main types of skin cleansing products are known. Foaming detergent aqueous lotions and gels, rinsable cleansing anhydrous oils and gels, and foaming creams.
Rinsable anhydrous oils and gels cleanse by virtue of the oils present in these formulations. These oils make it possible to dissolve fatty residues and to disperse make-up pigments. These products are effective and well tolerated. However, they are disadvantageous in that they are heavy, do not foam, and do not confer a feeling of freshness on application.
Foaming detergent aqueous lotions and gels cleanse by virtue of surfactants, which suspend the fatty residues and the pigments of the make-up products. They are effective and pleasant to use because they foam and because they are easy to remove. However, the lotions are generally fairly fluid, which makes them sometimes tricky to handle, and it is difficult to thicken the gels while retaining good foaming properties.
In order to obtain good foaming performance while having a thick composition, attempts have been made to prepare foaming creams. However, foaming creams are often unstable in heat.
The term xe2x80x9cfoaming creamsxe2x80x9d is understood here to mean opaque and viscous compositions often sold in a tube and generally composed of an aqueous medium comprising a mixture of surfactants, such as fatty acid salts (soaps) or anionic, nonionic or amphoteric synthetic surfactants, and of other additives, such as, for example, polymers, polyols or fillers.
These creams, intended in particular for cleansing the skin, foam when they are mixed with water. They can be used in two ways. The first use consists in spreading the cream over the hands, in applying it to the face or to the body, and then massaging it in the presence of water to develop the foam directly on the face or the body. The other possible use of this type of product consists in developing the foam in the palms of the hands before being applied to the face or the body. In both cases, the foam is subsequently rinsed off.
The majority of foaming creams currently available commercially are unstable above 40xc2x0 C. This means that, if they are stored for a few days at this temperature, they exhibit macroscopic phase separation, resulting in separation into at least two phases. Creams thus phase-separated at a temperature markedly higher than ambient temperature, could be heterogeneous after returning to ambient temperature, and, thus, are unusable because of the deterioration in texture and in the foaming properties. The term xe2x80x9cambient temperaturexe2x80x9d is understood here to mean a moderate temperature of approximately 20 to 25xc2x0 C.
It is essential for this type of product to be stable over a wide temperature range. This is because, during its life, the product can be exposed to temperatures ranging from xe2x88x9220xc2x0 C. to +45xc2x0 C. at minimum, depending upon the climatic, storage and/or transportation conditions. For example, it is necessary for a cream transported in a car to retain its stability, because of the risk of remaining exposed to the sun for a long period of time, to say at a temperature which can easily reach 50xc2x0 C. It is also necessary for these foaming creams to be able to be used in hot countries without their transportation and storage presenting a problem.
It is well known that it is possible to prevent phase separation of a foaming cream by increasing the consistency of the product subjected to temperatures of +40xc2x0 to +45xc2x0 C. by addition of polymers or of fillers. However, in this case, the product becomes very stiff at moderate ambient temperature and no longer exhibits the properties desired for application to the skin; in particular, it becomes difficult to mix the product with water and to make it foam.
The need thus remains for a foaming cream, stable up to at least 45xc2x0 C., the cream appearance of which is maintained at ambient temperature even after changing to a higher temperature and which has good foaming characteristics.
The inventors have discovered that it is possible to obtain a foaming composition in the form of a cream having good stability, even at temperatures from +40 to +45xc2x0 C., by using a surfactant system such that at least one para-crystalline phase of direct hexagonal or cubic type appears when the composition is heated to a temperature of greater than 30xc2x0 C. and such that this paracrystalline phase remains present up to at least 45xc2x0 C.
The fact that one paracrystalline phase of direct hexagonal or cubic type appears when the composition is heated to a temperature of greater than 30xc2x0 C. and that this paracrystalline phase remains present up to at least 45xc2x0 C., means that this phase is present at least at a temperature ranging from 30xc2x0 C. to 45xc2x0 C. It is also possible that the paracrystalline phase is present at temperatures above 45xc2x0 C. In addition, the paracrystalline phase of direct hexagonal or cubic type may be present at higher temperatures, as well.
To obtain the required stability, it is preferable for the paracrystalline phase formed (or liquid crystal) to be of the direct hexagonal phase type. It is not necessary for this paracrystalline phase to be present at ambient temperature but it must appear above a temperature of between 30xc2x0 C. and 45xc2x0 C.
Foaming creams which do not exhibit a phase organization as mentioned above are not generally stable at 45xc2x0 C. At this temperature, they undergo macroscopic phase separation between at least two phases and they are subsequently unsuitable for the desired use when they are again at ambient temperature.
Thus, a subject-matter of the present application is a foaming composition constituting a cream for topical application comprising, in an aqueous medium, a surfactant system such that at least one paracrystalline phase of direct hexagonal and/or cubic type appears when the temperature increases above 30xc2x0 C. and such that this paracrystalline phase remains present up to at least 45xc2x0 C.
The obtained composition constitutes a opaque cream which has very good cosmetic properties (softness, creaminess), gives good foam and has good stability for a long time and at elevated temperatures.
The paracrystalline phase or phases present above +30xc2x0 C. can be of direct hexagonal or cubic type or can be a mixture of these two phases or a mixture of one of these phases or of both these phases with a phase of lamellar type. The paracrystalline phase(s) preferably comprise(s) at least one direct hexagonal phase.
The terms xe2x80x9clamellar phasexe2x80x9d, xe2x80x9cdirect hexagonal phasexe2x80x9d and xe2x80x9ccubic phasexe2x80x9d are given, in the present application, the meanings which a person skilled in the art generally gives to them.
Thus, the term xe2x80x9clamellar phasexe2x80x9d (phase D according to Ekwall, see Advances in Liquid Crystals, vol. 1, page 1-143, Acad. Press, 1975, edited by G. H. Brown) is understood to mean a liquid crystal phase with plane symmetry comprising several amphiphilic bilayers arranged in parallel and separated by a liquid medium which is generally water.
The term xe2x80x9cdirect hexagonal phasexe2x80x9d (phase F according to Ekwall, see Advances in Liquid Crystals, vol. 1, page 1-143, Acad. Press, 1975, edited by G. H. Brown) is understood to mean a liquid crystal phase corresponding to a hexagonal arrangement of parallel cylinders composed of an amphiphil and separated by a liquid medium which is generally water. In a direct hexagonal phase, the continuous medium is aqueous.
The term xe2x80x9ccubic phasexe2x80x9d is understood to mean a phase organized in a bipolar manner into separate hydrophilic and lipophilic domains, in close contact which form a thermodynamically stable three-dimensional network with cubic symmetry. Such an organization has been described in particular in xe2x80x9cLa Recherchexe2x80x9d, Vol. 23, pp. 306-315, March 1992, and in xe2x80x9cLipid Technologyxe2x80x9d, Vol. 2, No. 2, pp. 42-45, April 1990. Depending upon the arrangement of the hydrophilic and lipophilic domains, the cubic phase is said to be of normal or inverted type. The term xe2x80x9ccubic phasexe2x80x9d used according to the present invention includes, of course, various types of cubic phases.
A more precise description of these phases can be found in Revue Francaise des Corps Gras, No. 2, February 1969, pp. 87 to 111 (Lachampt and Vila, xe2x80x9cTextures des phases paracristallinesxe2x80x9d [Textures of paracrystalline phases]).
Various techniques can be used to identify the constituent phases of the cream in particular, small-angle and large-angle X-ray diffraction measurements as well as observation by optical microscopy in polarized light.
X-ray Diffraction Technique
The X-ray diffraction technique is one of the most relevant for demonstrating the organization of paracrystalline phases, in particular within a sample. X-ray diffraction measurements can be carried out using a CGR Sigma 2060 generator equipped with an Inel tube comprising a Cu anticathode and a linear focusing chamber installed in symmetrical transmission. The samples are introduced at ambient temperature into a measurement cell closed off by Mylar or Capton windows and placed in a thermally regulated sample holder.
The diffraction spectra obtained with a wavelength xcex=1.54 angstroms (Kxcex1 line of copper) are recorded using a photostimulable phosphor screen scanned by a Molecular Dynamics PhosphorImager PSI laser scanning module. The detector/sample distance is adjusted to 133 mm, which gives access to lattice distances of between approximately 3 and 110 angstroms. The spectra are recorded at various set temperatures.
With this technique, the paracrystalline phases are characterized by the presence, at small diffraction angles, of a series of several fine lines due to Bragg reflections which correspond to distances: d1, d2 . . . dn with distance ratios d1/d1, d1/d2, . . . , d1/dn which are characteristic of each type of phase, as indicated, for example, in xe2x80x9cLa structure des colloxc3xafdes d""association I. Les phases liquides cristallines des systxc3xa9mes amphiphile-eauxe2x80x9d [The structure of association colloids, I. The crystalline liquid phases of amphiphile-water systems], V. Luzzati, H. Mustachi, A. Skoulios and F. Husson, Acta Cryst. (1960), 13, 660-667 or in Biochimica et Biophysica Acta (1990), 1031, pp. 1 to 69, by J. M. Seddon. Thus, for a phase with a lamellar structure and in particular for the paracrystalline phase of fluid lamellar type generally denoted by Lxcex1 and also known as neat phase, the distance ratios are equal to: 1, 2, 3, 4, . . . For the paracrystalline phase of direct hexagonal type generally denoted by H1 or E and also known as middle phase, the distance ratios are equal to: 1, {square root over ( )}3, 2, {square root over ( )}7, . . . At large diffraction angles, the paracrystalline phases exhibit a band centred over a distance of the order of 4.5 angstroms, whereas the crystalline phases result in fine lines.
Observations By Optical Microscopy
Observations by optical microscopy in polarized light also contribute to the identification of paracrystalline phases, in particular when the number of lines observed by X-ray diffraction is insufficient to unambiguously establish the nature of the paracrystalline phases present.
Optical microscopy observations in polarized light are carried out, for example, using a Laborlux S (Leitz) microscope equipped with an objective with a magnification of 10, with a system of cross polarizers and with a heating stage (Mettler FP80/FP82). The sample is deposited between a microscope slide and a coverglass and covered with a second slide and the assembly is sealed via a Parafilm(copyright) seal. The observations are made at various set temperatures or by temperature scanning at 2xc2x0 C./min between ambient temperature and approximately 95xc2x0 C.
It is known, for example, that isotropic micellar solutions are non-birefringent, that paracrystalline phases of cubic type are also non-birefringent and that paracrystalline phases of direct or inverted hexagonal fluid lamellar type exhibit, in polarized light, various characteristic textures described, for example, in xe2x80x9cTextures des phases paracrystallines rencontrxc3xa9es dans les diagrammes d""xc3xa9quilibre: agents de surface, lipides, eauxe2x80x9d [Textures of paracrystalline phases encountered in equilibrium diagrams: surfactants, lipids, water], F. Lachampt and R. M. Vila, Revue Francaise des corps gras (1969), 2, 87-111 or in xe2x80x9cThe aqueous phase behavior of surfactantsxe2x80x9d, Robert G. Laughlin, Academic Press, (1996), pp. 521-546.
Surfactant System
The surfactant system used in the composition of the invention which makes it possible to obtain the appearance of a paracrystalline phase during heating to at least 30xc2x0 C. preferably comprises at least one water-soluble surfactant and at least one water-insoluble surfactant.
The term xe2x80x9cwater-soluble surfactantxe2x80x9d is understood to mean a surfactant which, at a concentration of 20 g/l in deionized water at a temperature of approximately 25xc2x0 C., gives a transparent isotropic solution.
Conversely, the term xe2x80x9cwater-insoluble surfactantxe2x80x9d is understood to mean a surfactant which, at a concentration of 20 g/l in deionized water at a temperature of approximately 25xc2x0 C., gives a cloudy solution, indicating nondissolution of the surfactant in water.
The water-insoluble surfactants form a dispersed phase in the aqueous medium, this dispersed phase comprising all water-insoluble compounds.
Having water-insoluble surfactants allows improvement in the quality of the foam and the creaminess of the composition.
Water-Soluble Surfactants
Any water-soluble surfactant may be used. They are preferably foaming surfactants, that is to say surfactants capable of foaming in the presence of water. They are mainly anionic, nonionic or amphoteric derivatives having sufficiently short fatty chains for these products to be thoroughly soluble at ambient temperature in the aqueous solvent medium of the composition. A water-soluble surfactant or a mixture of such surfactants may be used.
Mention may be made, as water-soluble surfactants, of, for example, anionic surfactants, amphoteric and zwitterionic surfactants, and non-ionic surfactants.
Anionic Surfactants
According to an embodiment of the invention, the surfactant system used preferably comprises at least one water-soluble anionic surfactant and more particularly at least one water-soluble carboxylic acid or one water-soluble carboxylic acid salt, which salt is obtained from the acid and a base. The carboxylic acids which can be used are fatty acids, comprising a saturated or unsaturated linear or branched alkyl chain, having from 6 to 16 carbon atoms and preferably 10 to 14 carbon atoms. The salts of such fatty acids constitute soaps. The fact that the soap is water-soluble or not depends on the length of the alkyl chain and on the counterion constituting the salt. Use may be made, as salts, of, for example, alkali metal salts, alkaline earth metal salts, ammonium salts, aminoalcohol salts and amino acid salts, and in particular of sodium, potassium, magnesium, triethanolamine, N-methylglucamine, lysine and arginine salts. The bases which can be used to produce these salts can, for example, be inorganic bases, such as alkali metal hydroxides (sodium hydroxide and potassium hydroxide), alkaline earth metal hydroxides (magnesium hydroxide) or ammonium hydroxide, or organic bases, such as triethanolamine, N-methylglucamine, lysine and arginine. The carboxylic acid can in particular be lauric acid or myristic acid.
Mention may be made, as water-soluble soap, of, for example, potassium salts of C10 to C14 fatty acids and in particular the potassium salt of lauric acid, the potassium salt of myristic acid and their mixtures.
Soap is generally introduced into the composition in the form of a base, on the one hand, and of the fatty acid, on the other hand, the formation of the salt taking place in situ. Thus, when the water-soluble soap is composed of the potassium salt of lauric acid and/or of the potassium salt of myristic acid, the composition can then comprise lauric acid and/or myristic acid with a sufficient amount of potassium hydroxide to form the potassium salts of lauric acid and/or of myristic acid.
Mention may be made, as other anionic surfactants which can be used in the composition of the invention as water-soluble surfactant, of, for example, ethoxylated carboxylic acids and their salts; sarcosinates and acylsarconisates and their salts, such as sodium lauroyl sarcosinate; taurates and methyl-taurates and their salts; isethionates and acyl-isethionates, reaction products of fatty acids comprising from 10 to 22 carbon atoms with isethionic acid, and their salts, such as sodium isethionate and sodium cocoyl isethionate; sulphosuccinates and their salts; alkyl sulphates and alkyl ether sulphates and their salts, in particular sodium or triethanolamine lauryl sulphate and sodium or potassium lauryl ether sulphate; monoalkyl and dialkyl esters of phosphoric acid and their salts, such as, for example, sodium mono- and dilauryl phosphate, potassium mono- and dilauryl phosphate, triethanolamine mono- and dilauryl phosphate, sodium mono- and dimyristyl phosphate, potassium mono- and dimyristyl phosphate, diethanolamine mono- and dimyristyl phosphate, or triethanolamine mono- and dimyristyl phosphate; alkane-sulphonates and their salts; bile salts, such as cholates, deoxycholates, taurocholates or taurodeoxy-cholates; lipoamino acids and their salts, such as mono- and disodium acylglutamates; or bipolar geminal surfactants, such as described in Surfactant Science series, Vol. 74, published by Krister Homberg.
Amphoteric and Zwitterionic Surfactants
Mention may be made, as amphoteric or zwitterionic surfactants which can be used as water-soluble surfactants, of, for example, betaines, such as dimethylbetaine, coco-betaine and cocamidopropyl betaine; sulphobetaines, such as cocamidopropyl hydroxysultaine; alkylamphoacetates, such as cocoamphodiacetate; and their mixtures.
Nonionic Surfactants
Mention may be made, as nonionic surfactants capable of being used as water-soluble surfactants, of, for example, polyol ethers comprising fatty chains (8 to 30 carbon atoms), such as oxyethylenated sorbitol or glycerol fatty ethers; polyglycerol ethers and esters; polyoxyethylenated fatty alcohols which are ethers formed of ethylene oxide units and of at least one fatty alcohol chain having from 10 to 22 carbon atoms, the solubility of which depends on the ethylene oxide number and on the length of the fatty chain; for example, for a fatty chain comprising 12 carbon atoms, the ethylene oxide number must be greater than 7, and mention may be made, as examples of polyoxyethylenated fatty alcohols, of lauryl alcohol ethers comprising more than 7 oxyethylene groups; alkyl polyglucosides, the alkyl group for which comprises from 1 to 14 carbon atoms (alkyl-C1-C14 polyglucosides), such as, for example, decyl glucoside, lauryl glucoside or cocoyl glucoside; alkyl glucopyranosides and alkyl thioglucopyranosides; alkyl maltosides; alkyl-N-methylglucamides; polyoxyethylenated sorbitan esters which generally comprise from 1 to 100 ethylene glycol units and preferably from 2 to 40 ethylene oxide (OE) units; aminoalcohol esters; and their mixtures.
The surfactant system used in the composition of the invention comprises a content of water-soluble surfactant(s) which can range, for example, from 10 to 50% by weight (as active material), preferably from 15 to 35% by weight, with respect to the total weight of the composition. According to a preferred embodiment of the invention, the surfactant system in the composition of the invention comprises at least 10% by weight, preferably at least 15% by weight and more preferably at least 20% by weight of water-soluble surfactant(s) with respect to the total weight of the composition.
Water-Insoluble Surfactants
The water-insoluble surfactants contribute in particular the texture (consistency) of the final composition. Furthermore, in the temperature range between approximately 25xc2x0 C. and 45xc2x0 C., these surfactants partially associate with the water-soluble surfactants to contribute to the formation of the paracrystalline phase (preferably direct hexagonal phase) which is the source of the stability of the product up to at least 45xc2x0 C.
Mention may in particular be made, as water-insoluble surfactants used in the composition according to the invention, of water-insoluble carboxylic acids and their salts, which salts are obtained from the acid and a base, and thus of water-insoluble soaps, that is to say carboxylic acid salts, comprising a saturated or unsaturated, linear or branched alkyl chain, having from 6 to 30 carbon atoms and preferably 12 to 22 carbon atoms. For the derivatives comprising a single saturated fatty chain, the chain advantageously comprises from 12 to 32 carbon atoms, preferably from 14 to 22 carbon atoms and better still from 16 to 20 carbon atoms. For the derivatives comprising a mono-unsaturated or polyunsaturated or branched fatty chain, the chain advantageously comprises from 16 to 34 carbon atoms and preferably from 18 to 24 carbon atoms.
Mention may in particular be made, as carboxylic acid, of palmitic acid and stearic acid.
Use may be made, as salts, of alkali metal salts, alkaline earth metal salts, the ammonium salts, aminoalcohol salts and amino acid salts, and in particular of the sodium, potassium, magnesium, triethanolamine, N-methylglucamine, lysine and arginine salts. The bases which can be used to produce these salts can, for example, be inorganic bases, such as alkali metal hydroxides (sodium hydroxide and potassium hydroxide), alkaline earth metal hydroxides (magnesium hydroxide) or ammonium hydroxide, or organic bases, such as triethanolamine, N-methylglucamine, lysine and arginine.
Mention may be made, for example, as insoluble soap, of the sodium salt of C12 to C22 fatty acids and the potassium salt of C16 to C22 fatty acids and in particular of the potassium salt of palmitic acid and the potassium salt of stearic acid.
The soap is generally introduced into the composition in the form of the base, on the one hand, and of the fatty acid, on the other hand, for formation of the salt taking place in situ. Thus, when the insoluble soap is composed of the potassium salt of palmitic acid and/or of the potassium salt of stearic acid, the composition can then comprise palmitic acid and/or stearic acid with a sufficient amount of potassium hydroxide to form the potassium salts of palmitic acid and/or of stearic acid.
Mention may be made, as other surfactants which can be used in the composition of the invention as insoluble surfactant, of, for example, insoluble nonionic or anionic surfactants, such as esters of glycerol and of fatty acids comprising from 14 to 30 carbon atoms, such as glyceryl stearate; alkyl polyglucosides, the alkyl group for which comprises from 15 to 30 carbon atoms (alkyl-C15-C30 polyglucosides), such as, for example, cetostearyl glucoside; optionally oxyethylenated sterol and phytosterol derivatives; alkaline salts of cholesterol sulphate and in particular the sodium salt; alkaline salts of cholesterol phosphate and in particular the sodium salt; polyoxyethylenated fatty alcohols comprising an oxyethylene chain having a small number of oxyethylene groups and in particular less than 10 oxyethylene groups; dialkyl phosphates, such as alkaline salts of dicetyl phosphate and in particular the sodium and potassium salts; alkaline salts of dimyristyl phosphate and in particular the sodium and potassium salts; lecithins; sphingomyelins; ceramides and their mixtures.
The surfactant system used in the composition of the invention preferably comprises a content of water-insoluble surfactant(s) ranging from 5 to 50% (as active material) and preferably from 5 to 30% by weight with respect to the total weight of the composition.
The surfactant system (water-soluble and insoluble surfactants) is present in the composition of the invention in an amount, as active material, which can range, for example, from 20 to 65% by weight and preferably ranges from 30 to 65% by weight and preferably better still from 40 to 60% by weight with respect to the total weight of the composition. The surfactant system preferably comprises an amount of water-soluble soap(s) of at least 10% by weight with respect to the total weight of the composition and an overall amount of (water-soluble and insoluble) soaps preferably of at least 20% by weight with respect to the total weight of the composition and preferably ranging from 30 to 40% by weight with respect to the total weight of the composition.
The aqueous medium of the foaming creams of the invention can comprise, in addition to water, one or more solvents chosen from lower alcohols comprising from 1 to 6 carbon atoms, such as ethanol; polyols, such as glycerol; glycols, such as butylene glycol, isoprene glycol, propylene glycol or polyethylene glycols, such as PEG-8; sorbitol; sugars, such as glucose, fructose, maltose, lactose or sucrose; and their mixtures. The amount of solvent(s) in the composition of the invention can range from 0.5 to 30% by weight and preferably from 5 to 20% by weight with respect to the total weight of the composition.
To obtain more or less fluid compositions, one or more thickening agents, in particular polymers, can be incorporated in the compositions of the invention in concentrations preferably ranging from 0.05 to 2% by weight with respect to the total weight of the composition.
Mention may be made, as examples of thickeners, of:
polysaccharide biopolymers, such as xanthan gum, guar gum, alginates or modified celluloses;
synthetic polymers, such as polyacrylics, for example Carbopol 980, sold by Goodrich, or acrylate/acrylo-nitrile copolymers, such as Hypan SS201, sold by Kingston;
inorganic thickeners, such as smectites or modified or unmodified hectorites, such as the Bentone products sold by Rheox, Laponite products sold by Southern Clay Products or the Veegum HS product sold by R. T. Vanderbilt;
their mixtures.
The compositions according to the invention constitute more or less fluid creams, the |G*| moduli of which have, at a temperature of 25xc2x0 C., values ranging from 102 to 105 Pa and the loss angles xcex4 of which range from 10 to 45xc2x0 for frequencies ranging from 10xe2x88x922 to 10 Hz.
|G*| and xcex4 are viscoelastic parameters used to measure the physical properties of viscoelastic fluids, as explained in xe2x80x9cAn introduction to rheologyxe2x80x9d by H. A. Barnes, J. F. Hutton and K. Walters, pages 46 to 54 (published by Elsevierxe2x80x941989).
|G*| is the modulus of the complex modulus G* and xcex4 is the loss angle. Gxe2x80x2 and Gxe2x80x3 are the components of G*: G*=Gxe2x80x2+iGxe2x80x3. Gxe2x80x2 and Gxe2x80x3 are respectively the storage modulus and the loss modulus and i is equal to (xe2x88x921)1/2. The components Gxe2x80x2 and Gxe2x80x3 of the complex modulus are obtained from the relationship between the oscillatory stress and the oscillatory strain.
The rheological measurements of |G*| and xcex4 are generally made using a Haake RS150 rheometer at a temperature of 25xc2x0 C. with measuring bodies possessing cone-plate geometry, the diameter of the cone and the size of the plate being 60 mm, and the angle of the cone being 2xc2x0 and the gap between the cone and the plate being 0.1 mm.
To make dynamic measurements of visco-elasticity (oscillatory measurements), first the linear viscoelastic region is determined by subjecting the sample to oscillatory stresses of increasing amplitudes and of constant frequency. The moduli are recorded as a function of the amplitude of the stress or of the amplitude of the strain, in order to determine the limits of the linear viscoelastic region. After having identified the linear viscoelastic region, dynamic measurements are made in the linear viscoelastic zone for a constant strain value lying in the linear visco-elastic region and at variable frequency. The Haake RS150 rheometer can cover a range of frequencies varying from 0.01 to 10 Hz (i.e. 0.063 to 62.8 rad/sec).
The following relationships are derived from the values of the amplitudes of the stress xcfx840 and of the strain xcex30 and from the loss angle xcex4:                               |                      G            *                    |                =                  xe2x80x83                ⁢                              τ            0                                γ            0                                                            G          xe2x80x2                =                  xe2x80x83                ⁢                  |                      G            *                    |                      cos            ⁢                          xe2x80x83                        ⁢            δ                                                            G          xe2x80x3                =                  xe2x80x83                ⁢                  |                      G            *                    |                      sin            ⁢                          xe2x80x83                        ⁢            δ                                                            G          *                =                  xe2x80x83                ⁢                              G            xe2x80x2                    +                      iG            xe2x80x3                              
The compositions of the invention can also comprise adjuvants commonly used in the field of foaming cleaners, such as cationic polymers of the polyquaternium type, which contribute softness and creaminess to the foaming cream. These cationic polymers may preferably be chosen from the following polymers:
Polyquaternium 5, such as the product Merquat(copyright) 5 sold by Calgon (copyright);
Polyquaternium 6, such as the product Salcare(copyright) SC 30 sold by Ciba(copyright) and the product Merquat(copyright) 100 sold by Calgon(copyright);
Polyquaternium 7, such as the products Merquat(copyright) S, Merquat(copyright) 2200 and Merquat(copyright) 550 sold by Calgon(copyright) and the product Salcare(copyright) SC 10 sold by Ciba(copyright);
Polyquaternium 10, such as the product Polymer JR400 sold by Amerchol(copyright);
Polyquaternium 11, such as the products Gafquat(copyright)755, Gadquat (copyright) 755N and Guafquat(copyright) 734 sold by ISP;
Polyquaternium 15, such as the product Rohagit(copyright) KF 270 F sold by Rohm;
Polyquaternium 16, such as the products Luviquat(copyright) FC905, Luviquat(copyright) FC370, Luviquat(copyright) HM552 and Luviquat(copyright) FC550 sold by BASF;
Polyquaternium 22, such as the product Merquat(copyright) 280 sold by Calgon(copyright);
Polyquaternium 28, such as the product Styleze(trademark) CC10 sold by ISP;
Polyquaternium 39, such as the product Merquat(copyright) Plus 3330 sold by Calgon(copyright);
Polyquaternium 44, such as the product Luviquat(copyright) Care sold by BASF(copyright);
Polyquaternium 46, such as the product Luviquat(copyright) Hold sold by BASF(copyright);
Polyquaternium 47, such as the product Merquat(copyright) 2001 sold by Calgon(copyright).
Use may also be made, as cationic polymer, of cationic guars, such as the product Jaguar sold by Rhodia.
In addition, the compositions of the invention can comprise adjuvants commonly used in the cosmetic field chosen from oils, active agents, fragrances, preservatives, sequestering agents (EDTA), pigments, pearlescent agents, inorganic or organic fillers, such as talc, kaolin, silica powder or polyethylene powder, soluble dyes or sunscreen agents. The amounts of these various adjuvants are those conventionally used in the field under consideration, for example from 0.01 to 20% of the total weight of the composition. These adjuvants and their concentrations must be such that they do not modify the property desired for the composition of the invention.
As oils, may be used for example oils of plant origin (jojoba oil, avocado oil, sesame oil, sunflower oil, corn oil, soybean oil, safflower oil or grape pip oil), mineral oils (petroleum jelly, optionally hydrogenated isoparaffins), synthetic oils (isopropyl myristate, cetearyl octanoate, polyisobutylene, ethylhexyl palmitate or alkyl benzoates), volatile or non-volatile silicone oils such as polydimethylsiloxanes (PDMSs) and cyclodimethylsiloxanes or cyclomethicones, and fluoro oils or fluorosilicone oils, as well as mixtures of these oils. The amount of oils must not modify the property desired for the composition of the invention: it is at most 15% of the total weight of the composition and preferably at most 10% of the total weight of the composition, and it is preferably from 0,1 to 5% of the total weight of the composition and preferably better still from 0,1 to 3% of the total weight of the composition.
Active agents which may be mentioned include for example moisturizers and, for example, protein hydrolysates and polyols such as glycerol, glycols, for instance polyethylene glycols, and sugar derivatives; natural extracts; procyannidol oligomers; vitamins; urea; caffeine; depigmenting agents such as kojic acid and caffeic acid; xcex1-hydroxy acids such as lactic acid and glycolic acid; retinoids; screening agents; extracts of algae, of fungi, of plants, of yeasts or of bacteria; hydrolysed, partially hydrolysed or nonhydrolysed proteins, enzymes, co-enzyme Q10 or ubiquinone, hormones, vitamins and their derivatives, flavonoides and isoflavones, and mixtures thereof.
The compositions according to the invention can constitute in particular foaming creams for topical application used in particular in the cosmetic or dermatological fields as products for cleaning or removing make-up from the skin (body or face, including eyes), scalp and/or hair. A composition for topical use comprises a physiologically acceptable medium, that is to say compatible with the skin, mucous membranes, scalp, eyes and/or hair. The composition can constitute more particularly a composition for cleansing the skin.
Another subject-matter of the invention is the cosmetic use of the composition as defined above as products for cleaning and/or removing make-up from the skin, scalp and/or hair.
Another subject-matter of the invention is a cosmetic process for removing grime from the skin, scalp and/or hair, characterized in that the composition of the invention is applied to the skin, to the scalp and/or to the hair in the presence of water, in that it is massaged to form a foam and in that the foam foamed and the grime are removed by rinsing with water.
The examples which follow serve to illustrate the invention without, however, exhibiting a limiting nature. The amounts shown are in % by weight, unless otherwise mentioned.